Novelty helmet



FIG. 1 is a front view of a novelty helmet showing my design;

FIG. 2 is a side view thereof;

FIG. 3 is a rear view thereof; and,

FIG. 4 is a top plan view thereof.

The details shown in broken lines in FIG. 1 form no part of the claimed design. 

I claim the ornamental design for a novelty helmet, as shown and described. 